includes/diff/DifferenceEngine.php

   1 <?php
   2 /**
   3  * User interface for the difference engine
   4  *
   5  * @file
   6  * @ingroup DifferenceEngine
   7  */
   8
   9 /**
  10  * Constant to indicate diff cache compatibility.
  11  * Bump this when changing the diff formatting in a way that
  12  * fixes important bugs or such to force cached diff views to
  13  * clear.
  14  */
  15 define( 'MW_DIFF_VERSION', '1.11a' );
  16
  17 /**
  18  * @todo document
  19  * @ingroup DifferenceEngine
  20  */
  21 class DifferenceEngine extends ContextSource {
  22         /**#@+
  23          * @private
  24          */
  25         var $mOldid, $mNewid;
  26         var $mOldtext, $mNewtext;
  27         protected $mDiffLang;
  28
  29         /**
  30          * @var Title
  31          */
  32         var $mOldPage, $mNewPage;
  33         var $mRcidMarkPatrolled;
  34
  35         /**
  36          * @var Revision
  37          */
  38         var $mOldRev, $mNewRev;
  39         private $mRevisionsIdsLoaded = false; // Have the revisions IDs been loaded
  40         var $mRevisionsLoaded = false; // Have the revisions been loaded
  41         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  42         var $mCacheHit = false; // Was the diff fetched from cache?
  43
  44         /**
  45          * Set this to true to add debug info to the HTML output.
  46          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  47          * (bug 20601)
  48          */
  49         var $enableDebugComment = false;
  50
  51         // If true, line X is not displayed when X is 1, for example to increase
  52         // readability and conserve space with many small diffs.
  53         protected $mReducedLineNumbers = false;
  54
  55         // Link to action=markpatrolled
  56         protected $mMarkPatrolledLink = null;
  57
  58         protected $unhide = false; # show rev_deleted content if allowed
  59         /**#@-*/
  60
  61         /**
  62          * Constructor
  63          * @param $context IContextSource context to use, anything else will be ignored
  64          * @param $old Integer old ID we want to show and diff with.
  65          * @param $new String either 'prev' or 'next'.
  66          * @param $rcid Integer ??? FIXME (default 0)
  67          * @param $refreshCache boolean If set, refreshes the diff cache
  68          * @param $unhide boolean If set, allow viewing deleted revs
  69          */
  70         function __construct( $context = null, $old = 0, $new = 0, $rcid = 0,
  71                 $refreshCache = false, $unhide = false )
  72         {
  73                 if ( $context instanceof IContextSource ) {
  74                         $this->setContext( $context );
  75                 }
  76
  77                 wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
  78
  79                 $this->mOldid = $old;
  80                 $this->mNewid = $new;
  81                 $this->mRcidMarkPatrolled = intval( $rcid );  # force it to be an integer
  82                 $this->mRefreshCache = $refreshCache;
  83                 $this->unhide = $unhide;
  84         }
  85
  86         /**
  87          * @param $value bool
  88          */
  89         function setReducedLineNumbers( $value = true ) {
  90                 $this->mReducedLineNumbers = $value;
  91         }
  92
  93         /**
  94          * @return Language
  95          */
  96         function getDiffLang() {
  97                 if ( $this->mDiffLang === null ) {
  98                         # Default language in which the diff text is written.
  99                         $this->mDiffLang = $this->getTitle()->getPageLanguage();
 100                 }
 101                 return $this->mDiffLang;
 102         }
 103
 104         /**
 105          * @return bool
 106          */
 107         function wasCacheHit() {
 108                 return $this->mCacheHit;
 109         }
 110
 111         /**
 112          * @return int
 113          */
 114         function getOldid() {
 115                 $this->loadRevisionIds();
 116                 return $this->mOldid;
 117         }
 118
 119         /**
 120          * @return Bool|int
 121          */
 122         function getNewid() {
 123                 $this->loadRevisionIds();
 124                 return $this->mNewid;
 125         }
 126
 127         /**
 128          * Look up a special:Undelete link to the given deleted revision id,
 129          * as a workaround for being unable to load deleted diffs in currently.
 130          *
 131          * @param int $id revision ID
 132          * @return mixed URL or false
 133          */
 134         function deletedLink( $id ) {
 135                 if ( $this->getUser()->isAllowed( 'deletedhistory' ) ) {
 136                         $dbr = wfGetDB( DB_SLAVE );
 137                         $row = $dbr->selectRow('archive', '*',
 138                                 array( 'ar_rev_id' => $id ),
 139                                 __METHOD__ );
 140                         if ( $row ) {
 141                                 $rev = Revision::newFromArchiveRow( $row );
 142                                 $title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
 143                                 return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
 144                                         'target' => $title->getPrefixedText(),
 145                                         'timestamp' => $rev->getTimestamp()
 146                                 ));
 147                         }
 148                 }
 149                 return false;
 150         }
 151
 152         /**
 153          * Build a wikitext link toward a deleted revision, if viewable.
 154          *
 155          * @param int $id revision ID
 156          * @return string wikitext fragment
 157          */
 158         function deletedIdMarker( $id ) {
 159                 $link = $this->deletedLink( $id );
 160                 if ( $link ) {
 161                         return "[$link $id]";
 162                 } else {
 163                         return $id;
 164                 }
 165         }
 166
 167         function showDiffPage( $diffOnly = false ) {
 168                 wfProfileIn( __METHOD__ );
 169
 170                 # Allow frames except in certain special cases
 171                 $out = $this->getOutput();
 172                 $out->allowClickjacking();
 173                 $out->setRobotPolicy( 'noindex,nofollow' );
 174
 175                 if ( !$this->loadRevisionData() ) {
 176                         // Sounds like a deleted revision... Let's see what we can do.
 177                         $t = $this->getTitle()->getPrefixedText();
 178                         $d = $this->msg( 'missingarticle-diff',
 179                                 $this->deletedIdMarker( $this->mOldid ),
 180                                 $this->deletedIdMarker( $this->mNewid ) )->escaped();
 181                         $out->setPageTitle( $this->msg( 'errorpagetitle' ) );
 182                         $out->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
 183                         wfProfileOut( __METHOD__ );
 184                         return;
 185                 }
 186
 187                 $user = $this->getUser();
 188                 $permErrors = $this->mNewPage->getUserPermissionsErrors( 'read', $user );
 189                 if ( $this->mOldPage ) { # mOldPage might not be set, see below.
 190                         $permErrors = wfMergeErrorArrays( $permErrors,
 191                                 $this->mOldPage->getUserPermissionsErrors( 'read', $user ) );
 192                 }
 193                 if ( count( $permErrors ) ) {
 194                         wfProfileOut( __METHOD__ );
 195                         throw new PermissionsError( 'read', $permErrors );
 196                 }
 197
 198                 # If external diffs are enabled both globally and for the user,
 199                 # we'll use the application/x-external-editor interface to call
 200                 # an external diff tool like kompare, kdiff3, etc.
 201                 if ( ExternalEdit::useExternalEngine( $this->getContext(), 'diff' ) ) {
 202                         $urls = array(
 203                                 'File' => array( 'Extension' => 'wiki', 'URL' =>
 204                                         # This should be mOldPage, but it may not be set, see below.
 205                                         $this->mNewPage->getCanonicalURL( array(
 206                                                 'action' => 'raw', 'oldid' => $this->mOldid ) )
 207                                 ),
 208                                 'File2' => array( 'Extension' => 'wiki', 'URL' =>
 209                                         $this->mNewPage->getCanonicalURL( array(
 210                                                 'action' => 'raw', 'oldid' => $this->mNewid ) )
 211                                 ),
 212                         );
 213
 214                         $externalEditor = new ExternalEdit( $this->getContext(), $urls );
 215                         $externalEditor->execute();
 216
 217                         wfProfileOut( __METHOD__ );
 218                         return;
 219                 }
 220
 221                 $rollback = '';
 222                 $undoLink = '';
 223
 224                 $query = array();
 225                 # Carry over 'diffonly' param via navigation links
 226                 if ( $diffOnly != $user->getBoolOption( 'diffonly' ) ) {
 227                         $query['diffonly'] = $diffOnly;
 228                 }
 229                 # Cascade unhide param in links for easy deletion browsing
 230                 if ( $this->unhide ) {
 231                         $query['unhide'] = 1;
 232                 }
 233
 234                 # Check if one of the revisions is deleted/suppressed
 235                 $deleted = $suppressed = false;
 236                 $allowed = $this->mNewRev->userCan( Revision::DELETED_TEXT, $user );
 237
 238                 # mOldRev is false if the difference engine is called with a "vague" query for
 239                 # a diff between a version V and its previous version V' AND the version V
 240                 # is the first version of that article. In that case, V' does not exist.
 241                 if ( $this->mOldRev === false ) {
 242                         $out->setPageTitle( $this->mNewPage->getPrefixedText() );
 243                         $out->addSubtitle( $this->msg( 'difference' ) );
 244                         $samePage = true;
 245                         $oldHeader = '';
 246                 } else {
 247                         wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 248
 249                         $sk = $this->getSkin();
 250                         if ( method_exists( $sk, 'suppressQuickbar' ) ) {
 251                                 $sk->suppressQuickbar();
 252                         }
 253
 254                         if ( $this->mNewPage->equals( $this->mOldPage ) ) {
 255                                 $out->setPageTitle( $this->mNewPage->getPrefixedText() );
 256                                 $out->addSubtitle( $this->msg( 'difference' ) );
 257                                 $samePage = true;
 258                         } else {
 259                                 $out->setPageTitle( $this->mOldPage->getPrefixedText() . ', ' . $this->mNewPage->getPrefixedText() );
 260                                 $out->addSubtitle( $this->msg( 'difference-multipage' ) );
 261                                 $samePage = false;
 262                         }
 263
 264                         if ( $samePage && $this->mNewPage->quickUserCan( 'edit', $user ) ) {
 265                                 if ( $this->mNewRev->isCurrent() && $this->mNewPage->userCan( 'rollback', $user ) ) {
 266                                         $out->preventClickjacking();
 267                                         $rollback = '&#160;&#160;&#160;' . Linker::generateRollback( $this->mNewRev );
 268                                 }
 269                                 if ( !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 270                                         $undoLink = ' ' . $this->msg( 'parentheses' )->rawParams(
 271                                                 Html::element( 'a', array(
 272                                                         'href' => $this->mNewPage->getLocalUrl( array(
 273                                                                 'action' => 'edit',
 274                                                                 'undoafter' => $this->mOldid,
 275                                                                 'undo' => $this->mNewid ) ),
 276                                                         'title' => Linker::titleAttrib( 'undo' )
 277                                                 ),
 278                                                 $this->msg( 'editundo' )->text()
 279                                         ) )->escaped();
 280                                 }
 281                         }
 282
 283                         # Make "previous revision link"
 284                         if ( $samePage && $this->mOldRev->getPrevious() ) {
 285                                 $prevlink = Linker::linkKnown(
 286                                         $this->mOldPage,
 287                                         $this->msg( 'previousdiff' )->escaped(),
 288                                         array( 'id' => 'differences-prevlink' ),
 289                                         array( 'diff' => 'prev', 'oldid' => $this->mOldid ) + $query
 290                                 );
 291                         } else {
 292                                 $prevlink = '&#160;';
 293                         }
 294
 295                         if ( $this->mOldRev->isMinor() ) {
 296                                 $oldminor = ChangesList::flag( 'minor' );
 297                         } else {
 298                                 $oldminor = '';
 299                         }
 300
 301                         $ldel = $this->revisionDeleteLink( $this->mOldRev );
 302                         $oldRevisionHeader = $this->getRevisionHeader( $this->mOldRev, 'complete' );
 303
 304                         $oldHeader = '<div id="mw-diff-otitle1"><strong>' . $oldRevisionHeader . '</strong></div>' .
 305                                 '<div id="mw-diff-otitle2">' .
 306                                         Linker::revUserTools( $this->mOldRev, !$this->unhide ) . '</div>' .
 307                                 '<div id="mw-diff-otitle3">' . $oldminor .
 308                                         Linker::revComment( $this->mOldRev, !$diffOnly, !$this->unhide ) . $ldel . '</div>' .
 309                                 '<div id="mw-diff-otitle4">' . $prevlink . '</div>';
 310
 311                         if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 312                                 $deleted = true; // old revisions text is hidden
 313                                 if ( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) ) {
 314                                         $suppressed = true; // also suppressed
 315                                 }
 316                         }
 317
 318                         # Check if this user can see the revisions
 319                         if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT, $user ) ) {
 320                                 $allowed = false;
 321                         }
 322                 }
 323
 324                 # Make "next revision link"
 325                 # Skip next link on the top revision
 326                 if ( $samePage && !$this->mNewRev->isCurrent() ) {
 327                         $nextlink = Linker::linkKnown(
 328                                 $this->mNewPage,
 329                                 $this->msg( 'nextdiff' )->escaped(),
 330                                 array( 'id' => 'differences-nextlink' ),
 331                                 array( 'diff' => 'next', 'oldid' => $this->mNewid ) + $query
 332                         );
 333                 } else {
 334                         $nextlink = '&#160;';
 335                 }
 336
 337                 if ( $this->mNewRev->isMinor() ) {
 338                         $newminor = ChangesList::flag( 'minor' );
 339                 } else {
 340                         $newminor = '';
 341                 }
 342
 343                 # Handle RevisionDelete links...
 344                 $rdel = $this->revisionDeleteLink( $this->mNewRev );
 345                 $newRevisionHeader = $this->getRevisionHeader( $this->mNewRev, 'complete' ) . $undoLink;
 346
 347                 $newHeader = '<div id="mw-diff-ntitle1"><strong>' . $newRevisionHeader . '</strong></div>' .
 348                         '<div id="mw-diff-ntitle2">' . Linker::revUserTools( $this->mNewRev, !$this->unhide ) .
 349                                 " $rollback</div>" .
 350                         '<div id="mw-diff-ntitle3">' . $newminor .
 351                                 Linker::revComment( $this->mNewRev, !$diffOnly, !$this->unhide ) . $rdel . '</div>' .
 352                         '<div id="mw-diff-ntitle4">' . $nextlink . $this->markPatrolledLink() . '</div>';
 353
 354                 if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 355                         $deleted = true; // new revisions text is hidden
 356                         if ( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 357                                 $suppressed = true; // also suppressed
 358                 }
 359
 360                 # If the diff cannot be shown due to a deleted revision, then output
 361                 # the diff header and links to unhide (if available)...
 362                 if ( $deleted && ( !$this->unhide || !$allowed ) ) {
 363                         $this->showDiffStyle();
 364                         $multi = $this->getMultiNotice();
 365                         $out->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 366                         if ( !$allowed ) {
 367                                 $msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 368                                 # Give explanation for why revision is not visible
 369                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 370                                         array( $msg ) );
 371                         } else {
 372                                 # Give explanation and add a link to view the diff...
 373                                 $link = $this->getTitle()->getFullUrl( $this->getRequest()->appendQueryValue( 'unhide', '1', true ) );
 374                                 $msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
 375                                 $out->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 376                         }
 377                 # Otherwise, output a regular diff...
 378                 } else {
 379                         # Add deletion notice if the user is viewing deleted content
 380                         $notice = '';
 381                         if ( $deleted ) {
 382                                 $msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
 383                                 $notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . $this->msg( $msg )->parse() . "</div>\n";
 384                         }
 385                         $this->showDiff( $oldHeader, $newHeader, $notice );
 386                         if ( !$diffOnly ) {
 387                                 $this->renderNewRevision();
 388                         }
 389                 }
 390                 wfProfileOut( __METHOD__ );
 391         }
 392
 393         /**
 394          * Get a link to mark the change as patrolled, or '' if there's either no
 395          * revision to patrol or the user is not allowed to to it.
 396          * Side effect: this method will call OutputPage::preventClickjacking()
 397          * when a link is builded.
 398          *
 399          * @return String
 400          */
 401         protected function markPatrolledLink() {
 402                 global $wgUseRCPatrol;
 403
 404                 if ( $this->mMarkPatrolledLink === null ) {
 405                         // Prepare a change patrol link, if applicable
 406                         if ( $wgUseRCPatrol && $this->mNewPage->quickUserCan( 'patrol', $this->getUser() ) ) {
 407                                 // If we've been given an explicit change identifier, use it; saves time
 408                                 if ( $this->mRcidMarkPatrolled ) {
 409                                         $rcid = $this->mRcidMarkPatrolled;
 410                                         $rc = RecentChange::newFromId( $rcid );
 411                                         // Already patrolled?
 412                                         $rcid = is_object( $rc ) && !$rc->getAttribute( 'rc_patrolled' ) ? $rcid : 0;
 413                                 } else {
 414                                         // Look for an unpatrolled change corresponding to this diff
 415                                         $db = wfGetDB( DB_SLAVE );
 416                                         $change = RecentChange::newFromConds(
 417                                                 array(
 418                                                 // Redundant user,timestamp condition so we can use the existing index
 419                                                         'rc_user_text'  => $this->mNewRev->getRawUserText(),
 420                                                         'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 421                                                         'rc_this_oldid' => $this->mNewid,
 422                                                         'rc_last_oldid' => $this->mOldid,
 423                                                         'rc_patrolled'  => 0
 424                                                 ),
 425                                                 __METHOD__
 426                                         );
 427                                         if ( $change instanceof RecentChange ) {
 428                                                 $rcid = $change->mAttribs['rc_id'];
 429                                                 $this->mRcidMarkPatrolled = $rcid;
 430                                         } else {
 431                                                 // None found
 432                                                 $rcid = 0;
 433                                         }
 434                                 }
 435                                 // Build the link
 436                                 if ( $rcid ) {
 437                                         $this->getOutput()->preventClickjacking();
 438                                         $token = $this->getUser()->getEditToken( $rcid );
 439                                         $this->mMarkPatrolledLink = ' <span class="patrollink">[' . Linker::linkKnown(
 440                                                 $this->mNewPage,
 441                                                 $this->msg( 'markaspatrolleddiff' )->escaped(),
 442                                                 array(),
 443                                                 array(
 444                                                         'action' => 'markpatrolled',
 445                                                         'rcid' => $rcid,
 446                                                         'token' => $token,
 447                                                 )
 448                                         ) . ']</span>';
 449                                 } else {
 450                                         $this->mMarkPatrolledLink = '';
 451                                 }
 452                         } else {
 453                                 $this->mMarkPatrolledLink = '';
 454                         }
 455                 }
 456
 457                 return $this->mMarkPatrolledLink;
 458         }
 459
 460         /**
 461          * @param $rev Revision
 462          * @return String
 463          */
 464         protected function revisionDeleteLink( $rev ) {
 465                 $link = Linker::getRevDeleteLink( $this->getUser(), $rev, $rev->getTitle() );
 466                 if ( $link !== '' ) {
 467                         $link = '&#160;&#160;&#160;' . $link . ' ';
 468                 }
 469                 return $link;
 470         }
 471
 472         /**
 473          * Show the new revision of the page.
 474          */
 475         function renderNewRevision() {
 476                 wfProfileIn( __METHOD__ );
 477                 $out = $this->getOutput();
 478                 $revHeader = $this->getRevisionHeader( $this->mNewRev );
 479                 # Add "current version as of X" title
 480                 $out->addHTML( "<hr class='diff-hr' />
 481                 <h2 class='diff-currentversion-title'>{$revHeader}</h2>\n" );
 482                 # Page content may be handled by a hooked call instead...
 483                 if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $out ) ) ) {
 484                         $this->loadNewText();
 485                         $out->setRevisionId( $this->mNewid );
 486                         $out->setRevisionTimestamp( $this->mNewRev->getTimestamp() );
 487                         $out->setArticleFlag( true );
 488
 489                         if ( $this->mNewPage->isCssJsSubpage() || $this->mNewPage->isCssOrJsPage() ) {
 490                                 // Stolen from Article::view --AG 2007-10-11
 491                                 // Give hooks a chance to customise the output
 492                                 // @TODO: standardize this crap into one function
 493                                 if ( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mNewPage, $out ) ) ) {
 494                                         // Wrap the whole lot in a <pre> and don't parse
 495                                         $m = array();
 496                                         preg_match( '!\.(css|js)$!u', $this->mNewPage->getText(), $m );
 497                                         $out->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
 498                                         $out->addHTML( htmlspecialchars( $this->mNewtext ) );
 499                                         $out->addHTML( "\n</pre>\n" );
 500                                 }
 501                         } elseif ( !wfRunHooks( 'ArticleViewCustom', array( $this->mNewtext, $this->mNewPage, $out ) ) ) {
 502                                 // Handled by extension
 503                         } else {
 504                                 // Normal page
 505                                 if ( $this->getTitle()->equals( $this->mNewPage ) ) {
 506                                         // If the Title stored in the context is the same as the one
 507                                         // of the new revision, we can use its associated WikiPage
 508                                         // object.
 509                                         $wikiPage = $this->getWikiPage();
 510                                 } else {
 511                                         // Otherwise we need to create our own WikiPage object
 512                                         $wikiPage = WikiPage::factory( $this->mNewPage );
 513                                 }
 514
 515                                 $parserOptions = ParserOptions::newFromContext( $this->getContext() );
 516                                 $parserOptions->enableLimitReport();
 517                                 $parserOptions->setTidy( true );
 518
 519                                 if ( !$this->mNewRev->isCurrent() ) {
 520                                         $parserOptions->setEditSection( false );
 521                                 }
 522
 523                                 $parserOutput = $wikiPage->getParserOutput( $parserOptions, $this->mNewid );
 524
 525                                 # WikiPage::getParserOutput() should not return false, but just in case
 526                                 if( $parserOutput ) {
 527                                         $out->addParserOutput( $parserOutput );
 528                                 }
 529                         }
 530                 }
 531                 # Add redundant patrol link on bottom...
 532                 $out->addHTML( $this->markPatrolledLink() );
 533
 534                 wfProfileOut( __METHOD__ );
 535         }
 536
 537         /**
 538          * Get the diff text, send it to the OutputPage object
 539          * Returns false if the diff could not be generated, otherwise returns true
 540          *
 541          * @return bool
 542          */
 543         function showDiff( $otitle, $ntitle, $notice = '' ) {
 544                 $diff = $this->getDiff( $otitle, $ntitle, $notice );
 545                 if ( $diff === false ) {
 546                         $this->getOutput()->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
 547                         return false;
 548                 } else {
 549                         $this->showDiffStyle();
 550                         $this->getOutput()->addHTML( $diff );
 551                         return true;
 552                 }
 553         }
 554
 555         /**
 556          * Add style sheets and supporting JS for diff display.
 557          */
 558         function showDiffStyle() {
 559                 $this->getOutput()->addModuleStyles( 'mediawiki.action.history.diff' );
 560         }
 561
 562         /**
 563          * Get complete diff table, including header
 564          *
 565          * @param $otitle Title: old title
 566          * @param $ntitle Title: new title
 567          * @param $notice String: HTML between diff header and body
 568          * @return mixed
 569          */
 570         function getDiff( $otitle, $ntitle, $notice = '' ) {
 571                 $body = $this->getDiffBody();
 572                 if ( $body === false ) {
 573                         return false;
 574                 } else {
 575                         $multi = $this->getMultiNotice();
 576                         return $this->addHeader( $body, $otitle, $ntitle, $multi, $notice );
 577                 }
 578         }
 579
 580         /**
 581          * Get the diff table body, without header
 582          *
 583          * @return mixed (string/false)
 584          */
 585         public function getDiffBody() {
 586                 global $wgMemc;
 587                 wfProfileIn( __METHOD__ );
 588                 $this->mCacheHit = true;
 589                 // Check if the diff should be hidden from this user
 590                 if ( !$this->loadRevisionData() ) {
 591                         wfProfileOut( __METHOD__ );
 592                         return false;
 593                 } elseif ( $this->mOldRev && !$this->mOldRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 594                         wfProfileOut( __METHOD__ );
 595                         return false;
 596                 } elseif ( $this->mNewRev && !$this->mNewRev->userCan( Revision::DELETED_TEXT, $this->getUser() ) ) {
 597                         wfProfileOut( __METHOD__ );
 598                         return false;
 599                 }
 600                 // Short-circuit
 601                 // If mOldRev is false, it means that the
 602                 if ( $this->mOldRev === false || ( $this->mOldRev && $this->mNewRev
 603                         && $this->mOldRev->getID() == $this->mNewRev->getID() ) )
 604                 {
 605                         wfProfileOut( __METHOD__ );
 606                         return '';
 607                 }
 608                 // Cacheable?
 609                 $key = false;
 610                 if ( $this->mOldid && $this->mNewid ) {
 611                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION,
 612                                 'oldid', $this->mOldid, 'newid', $this->mNewid );
 613                         // Try cache
 614                         if ( !$this->mRefreshCache ) {
 615                                 $difftext = $wgMemc->get( $key );
 616                                 if ( $difftext ) {
 617                                         wfIncrStats( 'diff_cache_hit' );
 618                                         $difftext = $this->localiseLineNumbers( $difftext );
 619                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 620                                         wfProfileOut( __METHOD__ );
 621                                         return $difftext;
 622                                 }
 623                         } // don't try to load but save the result
 624                 }
 625                 $this->mCacheHit = false;
 626
 627                 // Loadtext is permission safe, this just clears out the diff
 628                 if ( !$this->loadText() ) {
 629                         wfProfileOut( __METHOD__ );
 630                         return false;
 631                 }
 632
 633                 $difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
 634
 635                 // Save to cache for 7 days
 636                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 637                         wfIncrStats( 'diff_uncacheable' );
 638                 } elseif ( $key !== false && $difftext !== false ) {
 639                         wfIncrStats( 'diff_cache_miss' );
 640                         $wgMemc->set( $key, $difftext, 7 * 86400 );
 641                 } else {
 642                         wfIncrStats( 'diff_uncacheable' );
 643                 }
 644                 // Replace line numbers with the text in the user's language
 645                 if ( $difftext !== false ) {
 646                         $difftext = $this->localiseLineNumbers( $difftext );
 647                 }
 648                 wfProfileOut( __METHOD__ );
 649                 return $difftext;
 650         }
 651
 652         /**
 653          * Make sure the proper modules are loaded before we try to
 654          * make the diff
 655          */
 656         private function initDiffEngines() {
 657                 global $wgExternalDiffEngine;
 658                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 659                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 660                         wfDl( 'php_wikidiff' );
 661                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 662                 }
 663                 elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 664                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 665                         wfDl( 'wikidiff2' );
 666                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 667                 }
 668         }
 669
 670         /**
 671          * Generate a diff, no caching
 672          *
 673          * @param $otext String: old text, must be already segmented
 674          * @param $ntext String: new text, must be already segmented
 675          * @return bool|string
 676          */
 677         function generateDiffBody( $otext, $ntext ) {
 678                 global $wgExternalDiffEngine, $wgContLang;
 679
 680                 wfProfileIn( __METHOD__ );
 681
 682                 $otext = str_replace( "\r\n", "\n", $otext );
 683                 $ntext = str_replace( "\r\n", "\n", $ntext );
 684
 685                 $this->initDiffEngines();
 686
 687                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 688                         # For historical reasons, external diff engine expects
 689                         # input text to be HTML-escaped already
 690                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 691                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 692                         wfProfileOut( __METHOD__ );
 693                         return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 694                         $this->debug( 'wikidiff1' );
 695                 }
 696
 697                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 698                         # Better external diff engine, the 2 may some day be dropped
 699                         # This one does the escaping and segmenting itself
 700                         wfProfileIn( 'wikidiff2_do_diff' );
 701                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 702                         $text .= $this->debug( 'wikidiff2' );
 703                         wfProfileOut( 'wikidiff2_do_diff' );
 704                         wfProfileOut( __METHOD__ );
 705                         return $text;
 706                 }
 707                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 708                         # Diff via the shell
 709                         global $wgTmpDirectory;
 710                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 711                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 712
 713                         $tempFile1 = fopen( $tempName1, "w" );
 714                         if ( !$tempFile1 ) {
 715                                 wfProfileOut( __METHOD__ );
 716                                 return false;
 717                         }
 718                         $tempFile2 = fopen( $tempName2, "w" );
 719                         if ( !$tempFile2 ) {
 720                                 wfProfileOut( __METHOD__ );
 721                                 return false;
 722                         }
 723                         fwrite( $tempFile1, $otext );
 724                         fwrite( $tempFile2, $ntext );
 725                         fclose( $tempFile1 );
 726                         fclose( $tempFile2 );
 727                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 728                         wfProfileIn( __METHOD__ . "-shellexec" );
 729                         $difftext = wfShellExec( $cmd );
 730                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 731                         wfProfileOut( __METHOD__ . "-shellexec" );
 732                         unlink( $tempName1 );
 733                         unlink( $tempName2 );
 734                         wfProfileOut( __METHOD__ );
 735                         return $difftext;
 736                 }
 737
 738                 # Native PHP diff
 739                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 740                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 741                 $diffs = new Diff( $ota, $nta );
 742                 $formatter = new TableDiffFormatter();
 743                 $difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 744                 wfProfileOut( __METHOD__ );
 745                 return $difftext;
 746         }
 747
 748         /**
 749          * Generate a debug comment indicating diff generating time,
 750          * server node, and generator backend.
 751          * @return string
 752          */
 753         protected function debug( $generator = "internal" ) {
 754                 global $wgShowHostnames;
 755                 if ( !$this->enableDebugComment ) {
 756                         return '';
 757                 }
 758                 $data = array( $generator );
 759                 if ( $wgShowHostnames ) {
 760                         $data[] = wfHostname();
 761                 }
 762                 $data[] = wfTimestamp( TS_DB );
 763                 return "<!-- diff generator: " .
 764                 implode( " ",
 765                 array_map(
 766                                         "htmlspecialchars",
 767                 $data ) ) .
 768                         " -->\n";
 769         }
 770
 771         /**
 772          * Replace line numbers with the text in the user's language
 773          * @return mixed
 774          */
 775         function localiseLineNumbers( $text ) {
 776                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 777                 array( &$this, 'localiseLineNumbersCb' ), $text );
 778         }
 779
 780         function localiseLineNumbersCb( $matches ) {
 781                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 782                 return $this->msg( 'lineno' )->numParams( $matches[1] )->escaped();
 783         }
 784
 785
 786         /**
 787          * If there are revisions between the ones being compared, return a note saying so.
 788          * @return string
 789          */
 790         function getMultiNotice() {
 791                 if ( !is_object( $this->mOldRev ) || !is_object( $this->mNewRev ) ) {
 792                         return '';
 793                 } elseif ( !$this->mOldPage->equals( $this->mNewPage ) ) {
 794                         // Comparing two different pages? Count would be meaningless.
 795                         return '';
 796                 }
 797
 798                 if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
 799                         $oldRev = $this->mNewRev; // flip
 800                         $newRev = $this->mOldRev; // flip
 801                 } else { // normal case
 802                         $oldRev = $this->mOldRev;
 803                         $newRev = $this->mNewRev;
 804                 }
 805
 806                 $nEdits = $this->mNewPage->countRevisionsBetween( $oldRev, $newRev );
 807                 if ( $nEdits > 0 ) {
 808                         $limit = 100; // use diff-multi-manyusers if too many users
 809                         $numUsers = $this->mNewPage->countAuthorsBetween( $oldRev, $newRev, $limit );
 810                         return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 811                 }
 812                 return ''; // nothing
 813         }
 814
 815         /**
 816          * Get a notice about how many intermediate edits and users there are
 817          * @param $numEdits int
 818          * @param $numUsers int
 819          * @param $limit int
 820          * @return string
 821          */
 822         public static function intermediateEditsMsg( $numEdits, $numUsers, $limit ) {
 823                 if ( $numUsers > $limit ) {
 824                         $msg = 'diff-multi-manyusers';
 825                         $numUsers = $limit;
 826                 } else {
 827                         $msg = 'diff-multi';
 828                 }
 829                 return wfMessage( $msg )->numParams( $numEdits, $numUsers )->parse();
 830         }
 831
 832         /**
 833          * Get a header for a specified revision.
 834          *
 835          * @param $rev Revision
 836          * @param $complete String: 'complete' to get the header wrapped depending
 837          *        the visibility of the revision and a link to edit the page.
 838          * @return String HTML fragment
 839          */
 840         private function getRevisionHeader( Revision $rev, $complete = '' ) {
 841                 $lang = $this->getLanguage();
 842                 $user = $this->getUser();
 843                 $revtimestamp = $rev->getTimestamp();
 844                 $timestamp = $lang->userTimeAndDate( $revtimestamp, $user );
 845                 $dateofrev = $lang->userDate( $revtimestamp, $user );
 846                 $timeofrev = $lang->userTime( $revtimestamp, $user );
 847
 848                 $header = $this->msg(
 849                         $rev->isCurrent() ? 'currentrev-asof' : 'revisionasof',
 850                         $timestamp,
 851                         $dateofrev,
 852                         $timeofrev
 853                 )->escaped();
 854
 855                 if ( $complete !== 'complete' ) {
 856                         return $header;
 857                 }
 858
 859                 $title = $rev->getTitle();
 860
 861                 $header = Linker::linkKnown( $title, $header, array(),
 862                         array( 'oldid' => $rev->getID() ) );
 863
 864                 if ( $rev->userCan( Revision::DELETED_TEXT, $user ) ) {
 865                         $editQuery = array( 'action' => 'edit' );
 866                         if ( !$rev->isCurrent() ) {
 867                                 $editQuery['oldid'] = $rev->getID();
 868                         }
 869
 870                         $msg = $this->msg( $title->quickUserCan( 'edit', $user ) ? 'editold' : 'viewsourceold' )->escaped();
 871                         $header .= ' (' . Linker::linkKnown( $title, $msg, array(), $editQuery ) . ')';
 872                         if ( $rev->isDeleted( Revision::DELETED_TEXT ) ) {
 873                                 $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 874                         }
 875                 } else {
 876                         $header = Html::rawElement( 'span', array( 'class' => 'history-deleted' ), $header );
 877                 }
 878
 879                 return $header;
 880         }
 881
 882         /**
 883          * Add the header to a diff body
 884          *
 885          * @return string
 886          */
 887         function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
 888                 // shared.css sets diff in interface language/dir, but the actual content
 889                 // is often in a different language, mostly the page content language/dir
 890                 $tableClass = 'diff diff-contentalign-' . htmlspecialchars( $this->getDiffLang()->alignStart() );
 891                 $header = "<table class='$tableClass'>";
 892
 893                 if ( !$diff && !$otitle ) {
 894                         $header .= "
 895                         <tr valign='top'>
 896                         <td class='diff-ntitle'>{$ntitle}</td>
 897                         </tr>";
 898                         $multiColspan = 1;
 899                 } else {
 900                         if ( $diff ) { // Safari/Chrome show broken output if cols not used
 901                                 $header .= "
 902                                 <col class='diff-marker' />
 903                                 <col class='diff-content' />
 904                                 <col class='diff-marker' />
 905                                 <col class='diff-content' />";
 906                                 $colspan = 2;
 907                                 $multiColspan = 4;
 908                         } else {
 909                                 $colspan = 1;
 910                                 $multiColspan = 2;
 911                         }
 912                         $header .= "
 913                         <tr valign='top'>
 914                         <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 915                         <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 916                         </tr>";
 917                 }
 918
 919                 if ( $multi != '' ) {
 920                         $header .= "<tr><td colspan='{$multiColspan}' align='center' class='diff-multi'>{$multi}</td></tr>";
 921                 }
 922                 if ( $notice != '' ) {
 923                         $header .= "<tr><td colspan='{$multiColspan}' align='center'>{$notice}</td></tr>";
 924                 }
 925
 926                 return $header . $diff . "</table>";
 927         }
 928
 929         /**
 930          * Use specified text instead of loading from the database
 931          */
 932         function setText( $oldText, $newText ) {
 933                 $this->mOldtext = $oldText;
 934                 $this->mNewtext = $newText;
 935                 $this->mTextLoaded = 2;
 936                 $this->mRevisionsLoaded = true;
 937         }
 938
 939         /**
 940          * Set the language in which the diff text is written
 941          * (Defaults to page content language).
 942          * @since 1.19
 943          */
 944         function setTextLanguage( $lang ) {
 945                 $this->mDiffLang = wfGetLangObj( $lang );
 946         }
 947
 948         /**
 949          * Load revision IDs
 950          */
 951         private function loadRevisionIds() {
 952                 if ( $this->mRevisionsIdsLoaded ) {
 953                         return;
 954                 }
 955
 956                 $this->mRevisionsIdsLoaded = true;
 957
 958                 $old = $this->mOldid;
 959                 $new = $this->mNewid;
 960
 961                 if ( $new === 'prev' ) {
 962                         # Show diff between revision $old and the previous one.
 963                         # Get previous one from DB.
 964                         $this->mNewid = intval( $old );
 965                         $this->mOldid = $this->getTitle()->getPreviousRevisionID( $this->mNewid );
 966                 } elseif ( $new === 'next' ) {
 967                         # Show diff between revision $old and the next one.
 968                         # Get next one from DB.
 969                         $this->mOldid = intval( $old );
 970                         $this->mNewid = $this->getTitle()->getNextRevisionID( $this->mOldid );
 971                         if ( $this->mNewid === false ) {
 972                                 # if no result, NewId points to the newest old revision. The only newer
 973                                 # revision is cur, which is "0".
 974                                 $this->mNewid = 0;
 975                         }
 976                 } else {
 977                         $this->mOldid = intval( $old );
 978                         $this->mNewid = intval( $new );
 979                         wfRunHooks( 'NewDifferenceEngine', array( $this->getTitle(), &$this->mOldid, &$this->mNewid, $old, $new ) );
 980                 }
 981         }
 982
 983         /**
 984          * Load revision metadata for the specified articles. If newid is 0, then compare
 985          * the old article in oldid to the current article; if oldid is 0, then
 986          * compare the current article to the immediately previous one (ignoring the
 987          * value of newid).
 988          *
 989          * If oldid is false, leave the corresponding revision object set
 990          * to false. This is impossible via ordinary user input, and is provided for
 991          * API convenience.
 992          *
 993          * @return bool
 994          */
 995         function loadRevisionData() {
 996                 if ( $this->mRevisionsLoaded ) {
 997                         return true;
 998                 }
 999
1000                 // Whether it succeeds or fails, we don't want to try again
1001                 $this->mRevisionsLoaded = true;
1002
1003                 $this->loadRevisionIds();
1004
1005                 // Load the new revision object
1006                 $this->mNewRev = $this->mNewid
1007                         ? Revision::newFromId( $this->mNewid )
1008                         : Revision::newFromTitle( $this->getTitle() );
1009
1010                 if ( !$this->mNewRev instanceof Revision ) {
1011                         return false;
1012                 }
1013
1014                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
1015                 $this->mNewid = $this->mNewRev->getId();
1016                 $this->mNewPage = $this->mNewRev->getTitle();
1017
1018                 // Load the old revision object
1019                 $this->mOldRev = false;
1020                 if ( $this->mOldid ) {
1021                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1022                 } elseif ( $this->mOldid === 0 ) {
1023                         $rev = $this->mNewRev->getPrevious();
1024                         if ( $rev ) {
1025                                 $this->mOldid = $rev->getId();
1026                                 $this->mOldRev = $rev;
1027                         } else {
1028                                 // No previous revision; mark to show as first-version only.
1029                                 $this->mOldid = false;
1030                                 $this->mOldRev = false;
1031                         }
1032                 } /* elseif ( $this->mOldid === false ) leave mOldRev false; */
1033
1034                 if ( is_null( $this->mOldRev ) ) {
1035                         return false;
1036                 }
1037
1038                 if ( $this->mOldRev ) {
1039                         $this->mOldPage = $this->mOldRev->getTitle();
1040                 }
1041
1042                 return true;
1043         }
1044
1045         /**
1046          * Load the text of the revisions, as well as revision data.
1047          *
1048          * @return bool
1049          */
1050         function loadText() {
1051                 if ( $this->mTextLoaded == 2 ) {
1052                         return true;
1053                 } else {
1054                         // Whether it succeeds or fails, we don't want to try again
1055                         $this->mTextLoaded = 2;
1056                 }
1057
1058                 if ( !$this->loadRevisionData() ) {
1059                         return false;
1060                 }
1061                 if ( $this->mOldRev ) {
1062                         $this->mOldtext = $this->mOldRev->getText( Revision::FOR_THIS_USER );
1063                         if ( $this->mOldtext === false ) {
1064                                 return false;
1065                         }
1066                 }
1067                 if ( $this->mNewRev ) {
1068                         $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
1069                         if ( $this->mNewtext === false ) {
1070                                 return false;
1071                         }
1072                 }
1073                 return true;
1074         }
1075
1076         /**
1077          * Load the text of the new revision, not the old one
1078          *
1079          * @return bool
1080          */
1081         function loadNewText() {
1082                 if ( $this->mTextLoaded >= 1 ) {
1083                         return true;
1084                 } else {
1085                         $this->mTextLoaded = 1;
1086                 }
1087                 if ( !$this->loadRevisionData() ) {
1088                         return false;
1089                 }
1090                 $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
1091                 return true;
1092         }
1093 }